In recent years, communication systems introducing a femto cell base station are being developed in order to improve the quality of communication areas.
A femto cell base station is a small radio base station that covers a small communication area having a radius on the order of several tens of meters, intended to be installed in a room such as a home or office and the covers the communication area in the room. This allows the communication quality of the communication area that cannot be covered by an existing macro cell base station to be improved. Furthermore, the femto cell base station also allows the communication area to be covered without increasing costs in construction and improvement of infrastructure of the macro cell base station.
A system have been developed so far such that a femto cell base station is installed in a room of a home, office or the like and only a specific subscriber user (UE: User Equipment) is connected to a core network side via the femto cell base station (femto network) (e.g., see Patent Literatures 1 and 2).